Direct synthesis of a tetranuclear erbium(III) hydroxo cluster bearing a saturated Schiff base

The reaction of bis-5,5′-(2,2-dimethyl-1,3-propanediyldiimino)-2,2-dimethyl-4-hexen-3-one with tris[bis(trimethylsilyl)amido]erbium affords a five coordinate metal amido Schiff base (SB) complex which can be converted either stepwise or in situ into a neutral, tetranuclear Schiff base hydroxo cluster using H2O. Both complexes are reproducibly isolated in high yields with analytical purity and have been fully characterized. X-ray diffraction of the final hydrolysis product reveals a tetrameric [Er(μ3-OH)]4(SB)4 cubane structure with rigorous S4 symmetry. Each metal of the [Er(μ3-OH)]4 cube is also coordinated to a single tetradentate Schiff base in a monocapped trigonal prismatic arrangement.